Method for firing a ceramic and refractory metal casting core

a ceramic and refractory metal technology, applied in the field of investment casting, can solve the problems of insufficient temperature and time to adversely damage the non-ceramic casting core element, and achieve the effect of insufficient temperature and tim

Inactive Publication Date: 2007-10-11
RAYTHEON TECH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] The heating in the oxidative atmosphere may be effective to achieve binder removal from the ceramic casting core element. However, this heating advantageously is of insufficient temperature and time to adversely damage the non-ceramic casting core element. The second heating may be for a temperature and time effective to fire the ceramic. The non-oxidative atmosphere may thus protect the non-ceramic casting core element from excessive oxidation that would have occurred with a similar heating in an oxidative atmosphere.

Problems solved by technology

However, this heating advantageously is of insufficient temperature and time to adversely damage the non-ceramic casting core element.

Method used

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  • Method for firing a ceramic and refractory metal casting core
  • Method for firing a ceramic and refractory metal casting core
  • Method for firing a ceramic and refractory metal casting core

Examples

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Embodiment Construction

[0012]FIG. 1 shows an exemplary process 20 for forming a composite casting core. One or more refractory metal cores (RMCS) are formed 22. An exemplary formation includes a combination of cutting (e.g., laser cutting or stamping) from a refractory metal sheet (e.g., molybdenum or niobium), forming / shaping (e.g., said stamping or other bending), and coating with a protective coating. Suitable coating materials include silica, alumina, zirconia, chromia, mullite and hafnia. Preferably, the coefficient of thermal expansion (CTE) of the refractory metal and the coating are similar. Coatings may be applied by any appropriate line-of sight or non-line-of sight technique (e.g., chemical or physical vapor deposition (CVD, PVD) methods, plasma spray methods, electrophoresis, and sol gel methods). Individual layers may typically be 0.1 to 1 mil thick. Layers of Pt, other noble metals, Cr, Si, W, and / or Al, or other non-metallic materials may be applied to the metallic core elements for oxidati...

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Abstract

In an investment casting process, a composite core is formed as a combination of ceramic casting core element and a non-ceramic casting core element. The core is heated in an oxidative atmosphere and then heated in a non-oxidative atmosphere.

Description

BACKGROUND OF THE INVENTION [0001] The invention relates to investment casting. More particularly, it relates to the investment casting of superalloy turbine engine components. [0002] Investment casting is a commonly used technique for forming metallic components having complex geometries, especially hollow components, and is used in the fabrication of superalloy gas turbine engine components. The invention is described in respect to the production of particular superalloy castings, however it is understood that the invention is not so limited. [0003] Gas turbine engines are widely used in aircraft propulsion, electric power generation, and ship propulsion. In gas turbine engine applications, efficiency is a prime objective. [0004] Improved gas turbine engine efficiency can be obtained by operating at higher temperatures, however current operating temperatures in the turbine section exceed the melting points of the superalloy materials used in turbine components. Consequently, it is...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B22C9/10B22C9/04
CPCB22C9/04B22C9/12B22C9/103B22C1/16B22C7/02B22D27/04
Inventor BOCHIECHIO, MARIO P.BULLIED, STEVEN J.KENNARD, LEA D.VERNER, CARL R.MARCIN, JOHN J. JR.
Owner RAYTHEON TECH CORP
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